When processing aluminum alloy and engineering plastics, we will encounter the problem of workpiece deformation. Workpiece deformation is caused by many reasons. We need to analyze them one by one, find out the problems, and apply the right medicine to the case. Today, let's talk about how to deal with the deformation of the workpiece processed by the engineering plastic processing center.

What's the matter with the deformation of the workpiece processed by the engineering plastic processing center?

1. Firstly, the material and structure of the workpiece affect the deformation of the workpiece: the deformation is proportional to the complexity of the shape, the length-width ratio, and the wall thickness, and is proportional to the rigidity and stability of the material.

2. Deformation caused by workpiece clamping: during workpiece clamping, it is necessary to select the correct clamping point and select the appropriate clamping force according to the position of the clamping point.

3. Workpiece deformation caused by machining: due to the cutting force in the cutting process, the workpiece produces elastic deformation in the direction of the force, which is often referred to as the phenomenon of cutting.

4. Stress deformation after machining: after machining, there are internal stresses in the part itself. These internal stress distributions are in a relatively balanced state. The shape of the part is relatively stable, but the internal stress changes after removing some materials and heat treatment. At this time, the workpiece needs to reach the balance of stress again, so the shape changes.

The solution to deformation of workpiece processed by engineering plastic processing center

1. When designing parts, the influence of these factors on workpiece deformation should be minimized. In particular, the structure of large parts should be reasonable. Before processing, the hardness, looseness, and other defects of the blank should also be strictly controlled to ensure the quality of the blank and reduce the deformation of the workpiece.

2. Ensure that the clamping point is consistent with the support point so that the clamping force acts on the support. The clamping point should be as close to the machining surface as possible, and the position where the force is not easy to cause clamping deformation should be selected. When there are clamping forces acting in several directions on the workpiece, the sequence of clamping forces should be considered. For making the workpiece in contact with the support, the clamping force should act first, and it is not easy to be too large. For the main clamping force that balances the cutting force, it should act last.

Secondly, the contact area between workpiece and fixture should be increased or axial clamping force should be adopted. Increasing the rigidity of parts is an effective way to solve the clamping deformation, but due to the shape and structure characteristics of thin-walled parts, they have low rigidity. In this way, deformation will occur under the action of clamping force. Increasing the contact area between the workpiece and fixture can effectively reduce the deformation of the workpiece during clamping.

For example, when milling thin-walled parts, a large number of elastic pressing plates are used to increase the stress area of the contact parts; When turning the inner diameter and outer circle of the thin-walled sleeve, whether using a simple open transition ring or using an elastic mandrel, a full arc claw, etc., the contact area when clamping the workpiece is increased. This method is conducive to bearing the clamping force, to avoid the deformation of parts. The axial clamping force is also widely used in production. The design and manufacture of special fixtures can make the clamping force act on the end face, which can solve the bending deformation of the workpiece caused by the thin wall and poor rigidity of the workpiece.

3. When finishing, the tool is required to be sharp. On the one hand, it can reduce the resistance formed by the friction between the tool and the workpiece, on the other hand, it can improve the heat dissipation ability of the tool when cutting the workpiece, to reduce the residual internal stress on the workpiece.

Select high-speed machining. In high-speed machining, because the chips are removed in a short time, most of the cutting heat is taken away by the chips, which reduces the thermal deformation of the workpiece; Secondly, in high-speed machining, due to the reduction of the softening part of the cutting layer material, it can also reduce the deformation of parts processing, which is conducive to ensuring the size and shape accuracy of parts. In addition, cutting fluid is mainly used to reduce friction and cutting temperature in the cutting process. Rational use of cutting fluid plays an important role in improving the durability of cutting tools, machining surface quality, and machining accuracy. Therefore, to prevent the deformation of parts in machining, we must reasonably use sufficient cutting fluid.

Using reasonable cutting parameters in machining is the key factor to ensure the accuracy of parts. When machining thin-walled parts with high precision requirements, symmetrical machining is generally adopted to balance the stress generated on the opposite two sides to reach a stable state, and the workpiece is flat after machining. However, when a certain process adopts a large cutting amount, the workpiece will be deformed due to the imbalance of tensile stress and compressive stress.

The deformation of thin-walled parts during turning is multifaceted, including the clamping force when clamping the workpiece, the cutting force when cutting the workpiece, and the elastic and plastic deformation when the workpiece hinders the cutting tool, which increases the temperature of the cutting area and produces thermal deformation. Therefore, in rough machining, the back cutting and feed can be larger; During finish machining, the tool amount is generally 0.2 ~ 0.5mm, the feed rate is generally 0.1 ~ 0.2mm/r, or even smaller, and the cutting speed is 6 ~ 120m/min. During finish machining, the cutting speed should be as high as possible, but it is not easy to be too high. Select the cutting parameters reasonably, to achieve the purpose of reducing the deformation of parts.

4. Stack the workpiece that needs to be straightened into a certain height, presses it into a flat state with certain tooling, and then put the tooling and the workpiece into the heating furnace together, and select different heating temperatures and heating time according to the different part materials. After hot straightening, the internal structure of the workpiece is stable. At this time, the workpiece not only gets higher straightness but also the work hardening phenomenon is eliminated, which is more convenient for the further finishing of parts. The castings should be aged to eliminate the internal residual stress as much as possible and adopt the method of reprocessing after deformation, that is, rough machining aging reprocessing. For large parts, profiling processing should be adopted, that is, the deformation of the workpiece after assembly should be estimated, and the deformation should be reserved in the opposite direction during processing, which can effectively prevent the deformation of the parts after assembly.